<?php
/**
 * CGettextPoFile class file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CGettextPoFile represents a PO Gettext message file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.i18n.gettext
 * @since 1.0
 */
class CGettextPoFile extends CGettextFile
{
    /**
     * Loads messages from a PO file.
     * @param string $file file path
     * @param string $context message context
     * @return array message translations (source message => translated message)
     */
    public function load($file, $context)
    {
        $pattern = '/(msgctxt\s+"(.*?(?<!\\\\))")?\s+'
            . 'msgid\s+((?:".*(?<!\\\\)"\s*)+)\s+'
            . 'msgstr\s+((?:".*(?<!\\\\)"\s*)+)/';
        $matches = array();
        $n = preg_match_all($pattern, file_get_contents($file), $matches);

        $messages = array();
        for ($i = 0; $i < $n; $i++) {
            if ($matches[2][$i] === $context) {
                $id = $this->decode($matches[3][$i]);
                $message = $this->decode($matches[4][$i]);
                $messages[$id] = $message;
            }
        }
        return $messages;
    }

    /**
     * Saves messages to a PO file.
     * @param string $file file path
     * @param array $messages message translations (message id => translated message).
     * Note if the message has a context, the message id must be prefixed with
     * the context with chr(4) as the separator.
     */
    public function save($file, $messages)
    {
        $content = '';
        foreach ($messages as $id => $message) {
            if (($pos = strpos($id, chr(4))) !== false) {
                $content .= 'msgctxt "' . substr($id, 0, $pos) . "\"\n";
                $id = substr($id, $pos + 1);
            }
            $content .= 'msgid "' . $this->encode($id) . "\"\n";
            $content .= 'msgstr "' . $this->encode($message) . "\"\n\n";
        }
        file_put_contents($file, $content);
    }

    /**
     * Encodes special characters in a message.
     * @param string $string message to be encoded
     * @return string the encoded message
     */
    protected function encode($string)
    {
        return str_replace(
            array('"', "\n", "\t", "\r"),
            array('\\"', "\\n", '\\t', '\\r'),
            $string
        );
    }

    /**
     * Decodes special characters in a message.
     * @param string $string message to be decoded
     * @return string the decoded message
     */
    protected function decode($string)
    {
        $string = preg_replace(
            array('/"\s+"/', '/\\\\n/', '/\\\\r/', '/\\\\t/', '/\\\\"/'),
            array('', "\n", "\r", "\t", '"'),
            $string
        );
        return substr(rtrim($string), 1, -1);
    }
}
